The present invention relates generally to firearms and, more particularly, to a modular pistol and method for making the same by manufacturing and installing a breach face module into a pistol slide to simplify the manufacturing of the pistol.
There are ongoing efforts to improve the manufacturability of firearms. Although the basic manufacturing processes have not changed, including metal forging, turning and milling, new manufacturing methods and advancements in machinery in recent years have automated manufacturing processes that historically have been manually controlled. Many firearm components and assemblies are still manually assembled or fitted together to ensure safety and proper operation, and increase reliability.
A critical component in a semi-automatic pistol is the pistol slide assembly. At best, the slide assembly requires an extensive amount of machining time to produce, and the assembly often requires custom fitting with mating components in order to properly chamber and fire a round of ammunition, eject the spent cartridge, and load a new round. Any misalignment or improper fit of the slide and associated components can effect firearm operation and firing consistency.
The pistol slide is manufactured from a forged blank of metal using a series of metal milling, drilling, broaching and surfacing operations. The slide frame includes several features which are critical to the pistol""s performance and reliability. One such feature is the firing pin bore which contains the firing pin and firing pin spring. The firing pin travels through the firing pin bore and strikes the rear side of the ammunition cartridge to fire the pistol. If the firing pin bore is misaligned with the center of the cartridge, a misfire can occur that fails to fire the ammunition properly.
Machining the firing pin bore has proven to be very costly and labor intensive. The firing pin bore is long and narrow, and difficult to machine accurately. Conventional drilling is an inaccurate method to produce the bore because the thin, long drill bits typically used have a tendency to xe2x80x9cwalk,xe2x80x9d resulting in a mis-aligned bore. Electrode Discharge Milling (EDM) produces a more accurate bore but the process is time consuming and requires expensive machinery and tooling.
Another critical feature on the slide is the extractor arm which is a hook shaped member that extends into the firing chamber to grasp the rim of a spent cartridge and eject it from the pistol as the slide moves rearwardly after the pistol is fired. An extremely critical dimension to ensure proper ejectment of a spent cartridge is the axial distance between the engaging surface of the extractor arm hook and the pistol""s breach face, which forms the rear wall of a firing chamber and supports the cartridge in the firing position. When the pistol is fired, the extractor hook travels rearwardly with the slide and engages the cartridge rim to pull the cartridge from the rear of the barrel. If the axial distance is too small, the cartridge may be fed improperly to the chamber, resulting in a jammed condition known as xe2x80x9cfail to feed.xe2x80x9d If the distance is too large, the cartridge may not be ejected completely from the firing chamber, causing another jammed condition known as xe2x80x9cfail to extract.xe2x80x9d Either type of jam is unacceptable for the user and the firearm.
The machining steps required to properly locate the extractor arm are very time consuming and laborious due to the cumbersome and intricate nature of the slide frame. Typically, after the firing axis is established, the breach face and an extractor port are located and produced with a broaching operation. Various related features are then machined in the slide frame to mount the extractor arm with respect to the breach face. Because each feature of the slide is produced within an allowable machining tolerance, and the tolerances of some features in the slide effect the manufacturing accuracy of other slide features, it has proven difficult, and hence expensive, to properly locate the extractor arm accurately within the slide frame. Inaccuracies result in inconsistent firearm operation.
There have been attempts to introduce modular design concepts to firearms, or design high-wearing components so they are easily replaced or repaired. None of the efforts to date, however, have greatly simplified manufacturing and assembly procedures of the slide and extractor arm. One previous effort focused on retrofitting an existing pistol slide with a replaceable breach face module in the event the G/F wears excessively. In the course of normal use, a worn breach face can be replaced by a module that includes a new breach face. The problem with this component is that the original extractor arm of the pistol is left alone. Any manufacturing, assembly or operational problems with the original slide frame remain unresolved. Hence, the difficulties in correctly and efficiently machining the slide frame to locate the ejector arm still exist.
The firearm industry needs an improved method of manufacturing a pistol which improves manufacturing consistency and reliability of operation. The present invention is drawn toward such a method of manufacture and an article produced by the same.
It is an object of the present invention to provide a firearm with a pre-assembled breach face module which includes the breach face and the extractor arm.
It is another object of the present invention to provide a manufacture a breach face module for various firearm calibers which can be used with common components to produce firearms in a range of calibers.
It is yet another object of the present invention to manufacture a pistol slide body which can be used with pistols of various calibers. It is still another object of the present invention to manufacture a pistol slide according to a method which improves efficiency and reduces dimensional deviations that adversely effect pistol performance.
According to the present invention, a modular firearm is includes a pistol frame that slidably mounts a barrel and slide assembly on parallel frame rails, the slide assembly including a breach face module manufactured separately and mountable to the slide for locating a cartridge in a firing chamber and ejecting the cartridge from the pistol, the breach face module further comprising an extractor hook assembly and a lateral surface, both of which can be located to accommodate ammunition cartridges of various sizes.
One feature of the present invention is the slide frame which is dimensioned identically so that pistols in a range of different calibers can be manufactured cost effectively.
Another feature of the present invention is the pre-assembled breach face module which eliminates difficult manufacturing procedures when producing the pistol slide.
Still another feature of the present invention is the breach face module that is easily adapted for various caliber sizes by altering the dimensions of the breach face and the size and location of the extractor arm.
These and other objects, features and advantages of the present invention will become more apparent in the light of the following detailed description of best mode embodiments thereof as illustrated in the accompanying drawings.